CPA Series
OPERATING INSTRUCTIONS
Hot Swap
Hot swap is possible. The output voltages may deviate dynamically by
≤
5% during the plug-in / plug-out operation.
Output Characteristic and Protection
All outputs are fully protected against continuous opencircuit
(no load) and continuous short-circuit conditions.
All outputs of CPA250 models have a constant current
limitation with a rectangular characteristic. In addition, the total
power from outputs Vo1, Vo2, and Vo3 is limited to
P
o max
,
resulting in a free choice of load distribution between these
outputs. Output Vo4 is disabled in the case of overtemperature
generated by overcurrent.
In CPA500 model, the total power of all four outputs is limited
to
P
o max
.
In all models, all outputs are monitored for overvoltage
condition. If an overvoltage of 120 – 130% is dedected, the
converter is permanently disabled. To reset, the input voltage
must be removed for 60 seconds.
Thermal Considerations
If a converter is mounted in the upright position with
airflow as specified in the general conditions allowing
unrestricted forced-air cooling, and is operated at its
nominal input voltage and power at maximum ambient
temperature TA max (see Temperatures), the
temperature measured at the measurement point of the
case temperature TC (see Mechanical Data) will
approach after an initial warm-up phase the indicated
maximum value of TC max (105 °C). However, the
relationship between TA and TC depends heavily on the
operating conditions and system integration. The thermal
conditions are significantly influenced by the input
voltage, the output current, the airflow, and the
temperature of the adjacent elements and surfaces. TA
max is therefore only an indicative value (contrary to TC
max).
Caution
: The installer must ensure that under all operating
conditions
T
C
remains within the limits shown in the diagrams of
fig. 4.
Output power versus temperature T
A
at V
i nom
(CPD/CPA250)
Note
: Forced-air cooling or an additional heat sink can improve
the reliability or allow
T
A
to be increased above
T
A max
, provided
that
T
C max
is not exceeded.
Thermal Protection
A temperature sensor fitted on the main PCB provides an
overtemperature warning (degrade) signal 15 °C below
the temperature
T
c max
, at which the thermal derating
begins to reduce the output power. The output power
returns to the normal value, when the temperature drops
back below this limit; see
Temperature Warning and
Shutdown.
Output power versus temperature T
A
at V
i nom
(CPA500/550)
March 24, 2009
www.schroff.biz
73972-077/52
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